In storing and transporting a large number of sheets and other metal products, boards of various materials, and so on, it has been a common practice to put them on square timbers placed on the floor and fasten the articles and timbers together with straps or wires for easy forklift haulage or truck transportation.
With the growing scarcity of timber resources, however, square steel pipes have come to be used in place of wooden skids. Yet, square steel pipes, being hollow unlike wooden skids, may collapse if they are subjected to any great impact during transportation, thereby causing the bundle to give way or making the pipe skids no longer fit for reuse. Such collapse can be prevented by using heavy-wall square pipes, but, of course, at the expense of increasing cost. When heavywall square pipes are sent to distant destinations or when only a small number of them are used, it will be difficult to recover them economically, imposing an undesirable burden on pipe skid users. Heavy load can be supported also by light-wall square pipes, if only their number per bundle is large enough to withstand the weight. This condition, however, makes this method costly and necessitates extra labor in skid transportation and storage, strapping and wiring.
When a pile of articles that are apt to bend, such as steel sheets and plywood boards, are put on skids placed at intervals, the middle portion of the load usually bends or hangs down under its own weight. Even on such an occasion, if the skids are wood, their upper corners contacting the bottom of the mounted articles will get rounded following the way the articles bend and thereby inflict no scratch or damage to the articles, either the soft wooden skid corners getting deformed or the articles biting into them. If the skids are square steel pipes, on the other hand, their upper corners are too hard to deform as wooden skids might do, as a consequence of which the articles in the lower part of the bundle might break or otherwise damaged under the weight of the bundle.
Other type of metal skid than square pipes is the pallet skid device disclosed in U.S. Pat. No. 3,943,860. This skid comprises a horizontal member having legs extending from opposite ends thereof, with the horizontal member and legs each having a channel-like cross section for the purpose of reinforcement. For this type of skid having legs, it is difficult to support a heavy load because the legs are liable to break at their joint with the skid proper. The need to adjust the inter-leg space of each skid to the size of each individual article requires long manufacturing time and makes the skid costly.
U.S. Pat. No. 2,626,456 discloses a palletizing skid made of an ingot. The ingot has at its bottom a longitudinal channel, a deeper notch perpendicularly intersecting the channel, and a series of serrations. Although this skid is suited for supporting a heavy bundle, the great weight of the skid itself often causes inconvenience in handling.
U.S. Pat. No. 2,716,532 discloses a disposable skid made of flat sheet-like material such as fiber board. Although light in weight and convenient for handling, this skid is unsuited for supporting a heavy bundle.